Kubota M6800S Workshop Manual page 110

M6800 · M6800S · M8200 · M9000, WSM
(C) Servicing
Valve
1. Remove the valve cap (1) and the valve spring collets (2)
compressing the valve spring (4) with the valve spring retainer
(3).
(When reassembling)
• Install the intake valve spring with its small-pitch end downward
(at the head side).
• Wash the valve stem and valve guide hole, and apply engine oil
sufficiently.
• After installing the valve spring collets, lightly tap the stem to
assure proper fit with a plastic hammer.
(1) Valve Cap
(2) Valve Spring Collet
(3) Valve Spring Retainer
(4) Valve Spring
(5) Valve Stem Seal
(6) Valve
Cylinder Head Surface Flatness
1. Thoroughly clean the cylinder head surface.
2. Place a straightedge on the cylinder head's four sides (A), (B),
(C) and (D) and two diagonals (E) and (F) as shown in the figure.
Measure the clearance with a feeler gauge.
3. If the measurement exceeds the allowable limit, correct it with a
surface grinder.
IMPORTANT
• Do not place the straight edge on the combustion chamber.
• Be sure to check the valve recessing after correcting.
Cylinder head surface
Allowable limit
flatness
Cylinder Head Flaw
1. Prepare an air spray red check (Code No. 07909-31371).
2. Clean the surface of the cylinder head with detergent (1).
3. Spray the cylinder head surface with the red permeative liquid
(2). Leave it five to ten minutes after spraying.
4. Wash away the red permeative liquid on the cylinder head
surface with the detergent (1).
5. Spray the cylinder head surface with white developer (3).
6. If flawed, it can be identified as red marks.
(1) Detergent
(2) Red Permeative Liquid
1-S25
ENGINE
(7) Arm Bridge
(8) Large Pitch
(9) Smaller Pitch
(10) Install the spring with its smaller-
pitch end downward (at the head
side)
W1053044
0.05 mm
0.0020 in.
W1061323
(3) White developer
W1061416
KiSC issued 03, 2008 A